Potens Sanguine
by G.M.Rivers
Summary: Dudley Dursley is determined to show he is better than his freak cousin. What better way than to show everyone what it means to be a Dursley? When his science teacher asks him to choose a research topic, his answer is genetics, specifically, inheritance. As his research advances, he's in for a rude awakening.


Dudley Dursley gathered his books and started the slow trudge through the halls that was always followed by science class. Some students enjoyed it, but most of them dreaded the moment when they would have to stand forward and speak in front of Professor Bellwings' disapproving gaze. She always made the shyer students step in front of the class. In Dudley's opinion, she shouldn't even be allowed to teach in a classroom full of fourteen year olds, she was more suited for teaching at a penitentiary.

"Hello class! Today we will be choosing the topics for the end of term project. If you have any ideas write them in a small piece of paper and give it to Miss Jensen for my approval." Professor Bellwings paced in front of the board, her dark hair neatly arranged in a low bun on the nape of her neck. Dudley had never really liked Professor Bellwings, partly because she was, out of all of his professors, the sternest one, but mostly because she always seemed to treat him as if he were stupid.

Dudley Dursley wasn't a genius, not at all, and he knew he wasn't the smartest kid in class, but really didn't like being treated as if he were stupid. He would never admit it to anyone but that was one of the reasons why he disliked his cousin so much. He was a freak, sure, and that seemed to be the reason for his parents' dislike of Harry, but to Dudley it was more personal than that. Harry was smarter than Dudley. He knew it, the teachers knew it, he would even bet his parents knew it. It wouldn't have been such a personal offense if that was where it stopped, because even if Harry had a sharper mind, Dudley knew he was stronger, taller, and bigger than his cousin. However, as unintentional as it may have been, Petunia's attempts to make Harry hold back in class had only made Dudley feel even less smart, as his cousin often outperformed him even when he was holding back. Of course, it didn't help matters that Harry was a smart-arse. He didn't show it openly, Dudley's parents would have punished him severely if he had, but Dudley knew Harry well enough to see through the calm demeanor and notice the smirk he was holding back whenever Dudley made a particularly stupid mistake in class. Or when he failed to come up with a proper comeback. Or failed an exam. Or got turned down by a girl. Dudley was aware that other people didn't treat their cousins quite as badly as he did his, but he was also keenly aware that his cousin held no love for him and that he thought of him as nothing more than a fat bully with air instead of brains. That was the reason why Dudley had chosen his research subject as he had. Out of all the possible topics, he had chosen one of the hardest, not because he wanted a perfect grade, or to impress his teachers, but because he was going to prove, finally, that he was better than his freak cousin. Dudley had chosen to make his project about genetic inheritance, and of course, what it meant to be a Dursley. So as the teacher called for the students to share the topic of their choice, he felt no hesitation even as he saw the professor's skeptical look. He never expected that it would all go so wrong.

It all started when he tried to draw an inheritance tree for his family. It wasn't too hard to find the source of his eye, skin and hair color, but once he started on his mother's side of the inheritance tree, he stumbled upon a problem. The freaks. They were family, so they had to share some features with him, but he had no idea what his aunt looked like, he had never even seen a picture so how could he know if they shared any traits? Not that he wanted to share something with the freaks, but he knew, if he didn't get all of the information, his findings would be dismissed and they would give him the look he so hated. The one that said they knew all along that he would fail.

He tried asking his mother for a picture, play it off as curiosity, but she denied the petition so quickly one would think he had asked her for nudes. All further attempts failed miserably. The only answers Dudley managed to get from his mother were short, clipped, angry, and completely useless. Except for one small piece of information. His cousin had the same eye color as his aunt. That led to the realization that Harry might have inherited something more than just eye color, maybe his strange powers had been inherited too. After all, hadn't his mother always said that Harry's parents were both freaks? But if so, where did his mother's sister get it? Obviously, they shared the same parents, so the gene pool was the same. So… No, it couldn't be! Besides, his grandparents weren't freaks, so his aunt couldn't have gotten it from them, right?

Wrong. Dudley had almost managed to convince himself it was so, but it was only two days before he ran into some very damning information. Recessive genes. It wasn't necessary for his grandparents to be as Lily and Harry in order to carry the gene. In fact, if they both carried a freaky recessive gene and a normal dominant gene it made perfect sense for Lily Evans to have powers and for his mother to be normal, since there was only a 25% chance of inheriting both recessive genes. That also explained why his grandparents were, as far as he knew, normal. Were the circumstances different, Dudley might have felt proud of his research, as he had never worked quite as hard on anything else, but what his research implied had him more likely to never look as closely into anything else.

Logic said that his mother carried the gene. It wasn't certain, but seeing as she obviously wasn't a witch, the probability of it was over 66%. And if she did carry it, he had a 50% chance of carrying it. Dudley did not like those odds, especially once he found that if his father carried the gene from some distant freak ancestor, the probability of him turning out to be a wiz- freak -was as high as 25%.

When he finally managed to process that last piece of information, he felt sick. Petunia, seeing her suddenly ill-looking son fretted over him, "Dudley, sweetheart, are you feeling well? You seem pale… What's that your reading? Is it from the freak? I swear, if that boy made you upset-!"

"I need to be alone." Was all Dudley could manage, as he darted towards his room. He could only utter a short shout when his mother threatened to lock-up the boy when he came back for the summer, "It wasn't Harry!" The door slammed shut. The next few hours were some of the worst of his life as millions of unanswered questions flitted through his brain.

Was there any way his research could be wrong? Would his parents hate him if he had turned out to be like Harry? Would his own children turn out like Harry? What if he had never found this out? Would he hate them for something out of their control? Would he- would he treat them the way they treat Harry? Would his parents do the same to him? This time, he didn't just feel sick, he was.

He was- He couldn't- He wanted- He needed to talk to Harry.

That night, he spend hours upon hours scribbling away at a piece of paper, only to crumble the page up and start anew, over and over again. By the time he stopped, the alarm clock on his bedside had been reading A.M. for a few hours already and the floor of his room was littered with dozens of crumpled up balls of paper. This, he decided, was better dealt with in person. So for the first time in his life, Dudley Dursley made himself a promise he didn't intend to break. Come summer, he would fix this.

He never saw the snowy owl that had stopped outside his window, hoping for a break in between deliveries. He never saw the curious tilt of her head. He never noticed when the 39 balls of paper on the floor became 38.

One week later, when Dudley Dursley received a perfect grade for a paper he didn't remember writing, he simply assumed the Professor had mixed up his grade with someone else's and put it up to a happy accident. Far away from there, inside an office full with shiny clutter that hissed and buzzed, an old man with a long white beard smiled with grim satisfaction as he threw a crumpled piece of paper into the fireplace. After all, Voldemort had returned, precautions had to be taken. As the flames consumed the paper, in a matter of seconds, only three words remained visible and untouched: I'm sorry, Harry.

 **A/N**

 **Just realized I hadn't posted this on FFN, but instead only on AO3, so here you go. Really hope you liked!**

 **Initially, the story's name was going to be Birth of Magic... in Latin. However, google translate seemed to have some hilarious trouble with translating. It went like this, it translated birth of magic to ortum amet, but when I changed it back to English it translated as The Rise Carrots... wth. Then, when I translated THAT back to Latin (ortus sit amet) and back to English again... well, it said "He was born the mainstream" WTH Google! My mom looked at me is if I had gone crazy, why? Because I almost choked on my breakfast and then proceeded to laugh loudly.**

 **See you all later,**

 **GMR**


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